EUGENE, Ore. - U.S. researchers say a person who lives in a neighborhood with more fast food outlets and less opportunities to walk has a higher risk of weight gain.

The study, published in the American Journal of Epidemiology, finds neighborhoods having the highest amount of fast food outlets were associated with an increase of 3 pounds in weight and .8 inches in waist circumference in those who ate at fast food restaurants.

On the other hand, neighborhoods with high-walkability were associated with a decrease of 2.7 pounds in weight and 0.6 inches in waist size among residents, who increased their levels of vigorous physical activity during a one-year period.

"This is one of the few longitudinal studies that focus on change in individuals' body weight over time in relation to their lifestyle behaviors and immediate living environments," Fuzhong Li of the Oregon Research Institute in Eugene, Ore., said in a statement.

"The uniqueness of this study lies in its environment-person approach which we use to show that health-impeding environments, such as a high density of fast-food outlets, together with residents' behavior, such as eating fast food regularly, can have an unhealthy impact on body weight."

Health-promoting environments, such as walkable neighborhood streets, in conjunction with physically active residents, can have a positive impact on body weight over time, Li added.